Malaria parasites contain a plastid organelle called the apicoplast that is required for parasite survival in humans and for transmission to mosquitoes. The apicoplast has long been recognized as an important source of new drug targets to combat the inevitable problem of drug resistance, however, it has proven difficult to identify and validate apicoplast proteins that are essential for parasite survival. This goal is now achievable using new genetic tools in combination with metabolic bypass of the apicoplast. Blood stage parasites treated with the isoprene compound IPP (isopentenyl pyrophosphate) survive apicoplast inhibitors - even those which result in disruption of the organelle and loss of the organellar genome. Recently, we used the IPP metabolic bypass to demonstrate that iron-sulfur cluster biosynthesis is essential for maintenance of the organelle. We propose to use reverse and forward genetic approaches in conjunction with metabolic bypass to identify other nuclear-encoded proteins which are essential for apicoplast function and parasite survival. We will also use a new conditional localization tool to further characterize the roles of specific proteins and the phenotypes associated with their loss. Our experiments will help to build a more complete picture of the metabolic pathways and non-metabolic processes required for apicoplast function and parasite survival. Ultimately, we intend to identify novel targets and to validate known targets for future development of drugs to cure malaria and stop its transmission.